Abstract: A hydraulic piston unit including a rotational group for driving or being driven by a driving shaft, and having a tiltable displacement element for adjusting the displacement volume of the rotational group between a minimum or a maximum displacement, wherein, on t valve segment between a kidney-shaped inlet port and a kidney-shaped outlet port at respective dead end positions of reciprocally moveable working pistons first and second control ports are located in fluid connection with cylinder bores in the cylinder block, for controlling the position of the displacement element. The hydraulic piston unit further includes a control valve with a shiftable control valve spool fluidly connected via a high pressure port to a high pressure side of the hydraulic piston unit. The control valve spool is configured to conduct hydraulic fluid from the high pressure side to one of the first or the second control port.

Abstract: The self-contained energy efficient hydraulic actuator system of the present invention includes a hydraulic cylinder, a servo motor that is configured to produce rated torque from zero RPM to maximum rated RPM with rotor speed/position feedback to a servo motor, a pump, and a solenoid valve that enables the hydraulic cylinder to maintain its position without the motor running. The system has the ability to hold a load in place without motor operation via the use of the solenoid valve, and therefore saves energy and extends the motor lifetime by minimizing the motor running time.

Abstract: A hydrostatic system includes a hydraulic system and at least one sensor configured to monitor a parameter of the hydraulic system, the at least one sensor including a wireless transmitter configured to generate wireless transmissions based on the parameter. The hydrostatic system further includes an electronic control box including a wireless receiver that is configured to receive the wireless transmissions generated by the at least one sensor. The electronic control box is configured to control the hydraulic system based at least in part on the received wireless transmissions.

Abstract: In a drive device using a hydraulic pump controlled by a rotatable swash plate, the swash plate includes a pocket and a trunnion engaged to the pocket and rotatable about an axis of rotation offset from the swash plate axis of rotation. An interface is formed on a first end of the trunnion, and a first arcuate side of the interface engages a flat portion of the first side of the pocket as the trunnion is rotated in a first direction, and a second arcuate side of the interface engages a flat portion of the second side of the pocket as the trunnion is rotated in the opposite direction. The swash plate may also include at least one protrusion on a top surface extending in a direction perpendicular to swash plate axis of rotation to engage the housing and limit axial movement of the swash plate.

Abstract: The self-contained energy efficient hydraulic actuator system of the present invention includes a hydraulic cylinder, a servo motor that is configured to produce rated torque from zero RPM to maximum rated RPM with rotor speed/position feedback to a servo motor, a pump, and a solenoid valve that enables the hydraulic cylinder to maintain its position without the motor running. The system has the ability to hold a load in place without motor operation via the use of the solenoid valve, and therefore saves energy and extends the motor lifetime by minimizing the motor running time.

Abstract: A brake valve is insertable into a working line of a hydrostatic travel drive. The brake valve has a main stage with a first port connected to a variable displacement pump of the drive system and a second port connected to a motor of the drive system. The main stage has a slide piston positionable in a valve bore. In a freewheeling position, a connection is maximally open with minimal throttling between the two ports. In pressure-reducing positions, a regulable, throttled connection is open from the second to the first port to brake the motor. In pressure-limiting positions, a regulable, throttled connection is open from the first to the second port to begin to throttle a pressure medium flow from the variable displacement pump to a pressure protection mechanism. The positions lie on a center line of the main stage along which the slide piston is movable.

Abstract: A method including determining whether an OFF criterion is satisfied for a lag compressor of a tandem set of scroll compressors. The tandem set of scroll compressors includes a lead compressor. The method further includes: initiating at least one process when the OFF criterion is satisfied; and maintaining the lag compressor in an ON state for a predetermined period subsequent to the OFF criterion being satisfied. The at least one process includes at least one of: operating the lead compressor at a maximum level; overriding a motor overload protection method, wherein the motor overload protection method protects motors of the lead compressor and the lag compressor; and overriding a proportional integral derivative (PID) method to reduce a speed of a condenser fan. The PID method controls the speed of the condenser fan. A system including the lag compressor module and the lead compressor module.

Abstract: A method of controlling a hydraulic system having a variable displacement pump operatively coupled to an engine. The method includes detecting a speed of the engine, and determining a desired power value of the pump. The method also includes identifying an allowable power value that may be expended by the pump at the detected speed. The method also includes selecting a pump power value. The selected pump power value is the lower of the allowable power value and the desired power value. The method further includes adjusting the pump to deliver the selected pump power value.

Abstract: A beamless mechanic-reversing long stroke pumping unit is provided for petroleum production in diverse types of oil fields. Its mechanic-reversing system consists of differentials, brakes, etc. With two differentials assembled together, taper gears inside them perform revolution and rotation, enabling the pumping unit to achieve direction change and speed change mechanically. The stroke length of the pumping unit can reach 8 meters or longer, and the adjustment process is more convenient than most, by merely tuning the position of the proximity switches. Abrasion of the chains typically caused due to resetting of a motor frequently during operation, is eliminated in this pumping unit. The pumping unit has more reliable operation performance, more convenient maintenance, lower costs, better energy saving effects, and can be applied in land oil fields, offshore oil fields, oil wells with low permeability, etc.

Abstract: An automatic deactivation mechanism is configured for an air bladder pump having a casing and a motor located therein to pump air into an air bladder from the atmosphere and through an air valve connected through the casing. The automatic deactivation mechanism includes a housing positioned within the casing and has defined therethrough a first aperture in fluid communication with the atmosphere through the casing and a second aperture in fluid communication with the air bladder through the casing. Included within the housing are at least two switches and a diaphragm positioned between the switches. The housing is sealed so that when a threshold pressure is reached therein, at least one switch is triggered by deflection of the diaphragm to automatically deactivate the pump by de-energizing the motor.

Abstract: Plastic microfluidic structures having a substantially rigid diaphragm that actuates between a relaxed state wherein the diaphragm sits against the surface of a substrate and an actuated state wherein the diaphragm is moved away from the substrate. As will be seen from the following description, the microfluidic structures formed with this diaphragm provide easy to manufacture and robust systems, as well readily made components such as valves and pumps.

Abstract: A beamless mechanic-reversing long stroke pumping unit is provided for petroleum production in diverse types of oil fields. Its mechanic-reversing system consists of differentials, brakes, etc. With two differentials assembled together, taper gears inside them perform revolution and rotation, enabling the pumping unit to achieve direction change and speed change mechanically. The stroke length of the pumping unit can reach 8 meters or longer, and the adjustment process is more convenient than most, by merely tuning the position of the proximity switches. Abrasion of the chains typically caused due to resetting of a motor frequently during operation, is eliminated in this pumping unit. The pumping unit has more reliable operation performance, more convenient maintenance, lower costs, better energy saving effects, and can be applied in land oil fields, offshore oil fields, oil wells with low permeability, etc.

Abstract: A fuel system for a turbine engine is provided. The fuel system includes a positive displacement pump driven by an electric motor. The pump is rotated in a first direction to deliver fuel to the turbine engine, and a second direction for evacuating fuel from the turbine engine. A shut-off check valve is open in a first direction in response to a first differential pressure created by the pump in the first direction. The shut-off check valve is biased to a closed position when the pump is rotating in the second direction. An ecology check valve is biased to a closed position in the first direction and open in the second direction in response to a second differential pressure created by the pump. The check valves open and close automatically in response to the pressures generated by the positive displacement pump in each of the first and second rotational directions. In this manner, simple, reliable valves are utilized to regulate the flow of fuel in the fuel system.

Abstract: A device that relieves lubricant pressure in a divider block lubrication system into a fluid reservoir, a container, or directly back into the compressor frame to which the tubing is connected. This eliminates housekeeping, environmental, safety, and compressor component failure concerns associated with current atmospheric rupture assemblies that relieve directly to the atmosphere. The environmental compressor protection assembly contains a spring set to a pre-determined pressure. Lubricant pressure in excess of this pre-determined set pressure results in spring compression and opening of a relief path. The assembly preferably remains in a full open position and must be must be manually reset to the closed position to prevent fluid flow in the system. The relief path can lead to a fluid reservoir, a container, or directly back into the compressor frame. Flow of lubricant through the relief path results in loss of flow to the lubrication system.

Abstract: A method for starting a motor (14) with a bidirectional rotation direction, to rotate a fluid circulation centrifugal pump (10) having a predetermined optimum hydraulic efficiency depending on the starting rotation direction thereof. The method provides an initial motor (14) starting in either rotation direction, with subsequent pump (10) rotation in the same direction and, subsequently, a periodical interruption and restoration of the motor (14) power feeding as many times (N, N?) as to ensure the motor (14) starting, at least one or more times within a predetermined time interval (Ttot, Ts), in the rotation direction which corresponds to the predetermined pump (10) optimum hydraulic speed.

Abstract: A rotary compressor includes a driving shaft having an eccentric portion, a cylinder, and a roller installed on an outer circumference of the eccentric portion to contact an inner circumference of the cylinder, performing a rolling motion along the inner circumference and forming a fluid chamber to suck and compress fluid along with the inner circumference. A vane is installed elastically in the cylinder to contact the roller continuously. Discharge ports communicate with the fluid chamber. Suction ports communicate with the fluid chamber and are spaced apart from each other by a predetermined angle. A valve assembly selectively opens any one of the suction ports according to a rotation direction of the driving shaft. Compression spaces having different volumes are formed in the fluid chamber according to the rotation direction of the driving shaft such that two different compression capacities are formed.

Abstract: Embodiments generally provide an apparatus and method for processing substrates using a multi-chamber processing system (e.g., a cluster tool). In one embodiment, the cluster tool is adapted to perform a track lithography process in which a photosensitive material is applied to a substrate, patterned in a stepper/scanner, and then removed in a developing process completed in the cluster tool. In one embodiment of the cluster tool, substrates are grouped together in groups of two or more for transfer or processing to improve system throughput, reduce the number of moves a robot has to make to transfer a batch of substrates between the processing chambers, and thus increase system reliability. Embodiments also provide for a method and apparatus that are used to increase the reliability of the substrate transfer process to reduce system down time.

Abstract: Embodiments generally provide an apparatus and method for processing substrates using a multi-chamber processing system (e.g., a cluster tool) that has an increased system throughput, increased system reliability, substrates processed in the cluster tool have a more repeatable wafer history, and also the cluster tool has a smaller system footprint. Embodiments also provide for a method and apparatus that are used to improve the coater chamber, the developer chamber, the post exposure bake chamber, the chill chamber, and the bake chamber process results. Embodiments also provide for a method and apparatus that are used to increase the reliability of the substrate transfer process to reduce system down time.

Abstract: The invention relates to a hydraulic device with a supply line for pressurized hydraulic fluid and with a lubricating pump that is connected to the supply line in a fluidic fashion. The lubricating pump comprises a hydraulic inlet, a pump element for conveying a lubricant from a reservoir to at least one lubricating point of the hydraulic device, and mechanism for producing a pump stroke of the pump element. The mechanism for producing a pump stroke comprises a base body, a piston unit movable in the base body, and a reversing mechanism for reversing the direction of movement of at least one element of the piston unit.

Abstract: A carrying system includes first and second carrying machines each of which includes a holding unit, a base and a linkage having pivotally joined first and second links. The holding unit can be moved, by turning the second link relative to the first link which is turned relative to the base, along a substantially arc carrying route extending round the pedestal between a loading position and a processing position. The arc carrying route is closer to the pedestal with respect to an imaginary circle having its center on the pedestal and a radius corresponding to the distance between the pedestal and either of the loading position and the processing position.

Abstract: A container for receiving a detesting dust article and transporting thereof, which is mounted on a loader disposed in a border portion between a high cleanliness room and a low cleanliness room, including means by the use of which a cover thereof is opened and closed by an opener mechanism to communicate and shut the opening portion thereof and the high cleanliness room.

Abstract: The present invention relates to a supplementary lubrication system for an internal combustion engine operable to lubricate the engine and an accessory prior to engine start-up and to lubricate the accessory after engine shut-down. The supplementary lubrication system includes an oil source in fluid communication with a supplemental oil supply conduit, which branches to define two parallel conduits, a prelube branch and a postlube branch. Disposed within the prelube branch is a prelube one-way check valve and disposed within the postlube branch is a postlube one-way check valve. The prelube branch is in fluid communication with a first end of a two-directional pump and the postlube branch is in fluid communication with a second end of the two-directional pump.

Abstract: A hydrostatic radial piston machine 10 is proposed, whose adjustable reciprocating ring 18 has integrated means for detecting the eccentricity 20 between the reciprocating ring 18 and the rotor 14. In combination with the rotating rotor 14 and the binding of the sliding blocks 17 to this reciprocating ring 18, the eccentric location of the reciprocating ring 18 leads to a reciprocating motion of the work pistons 16 in a radial direction. Together with the kinematic conditions in the radial piston machine 10, this leads to a change in the spacing between two successive sliding blocks 17. This change in spacing varies in proportion to the eccentricity 20 of the reciprocating ring 18 and is therefore detected by a measuring instrument. To that end, this measuring instrument has a measured value pickup 27, which is integrated in the reciprocating ring 18 and outputs an increased voltage signal as long as sliding blocks 17, which act as measured value transducers, move past it.

Abstract: The present invention relates to a noise dampening assembly of a hydraulic machine and a drive motor, and provides for a structure comprising a block, in which the hydraulic machine is mounted by means of noise dampening elements.

Abstract: An electric-motor hydraulic pump includes a housing having a stationary internal shaft. A pair of cylinder blocks are rotatably carried by the shaft within the housing, and an array of pistons are slidably disposed with each cylinder block. A yoke plate is mounted within the housing and engages the pistons for determining displacement of the pistons within the cylinder blocks. Fluid inlet and outlet ports are provided in the housing and are coupled to the cylinder blocks. An induction motor includes a rotor carried by the cylinder block for corotation therewith, and a stator mounted within the housing surrounding the rotor. An electronic controller for controlling outlet fluid pressure and flow from the pump includes a plurality of sensors mounted on the housing for sensing operating characteristics of the pump and motor to provide electronic sensor signals as functions thereof.

Abstract: In a control (100) for a variable displacement hydraulic motor (12) having an electrically controlled hydraulic servo valve (14) for controlling the displacement of a hydraulic motor by varying position of a wobbler (28) in response to a servo valve control signal, a velocity transducer (72), coupled to a shaft (30) driven by the motor, for providing a velocity signal representative of the velocity of the shaft, and a wobbler position sensor (84), coupled to the wobbler, for producing a wobbler position signal indicative of the position of the wobbler, an improvement in accordance with the invention includes a controller (100) for producing the servo valve control signal as a function of a wobbler position command specifying a position of the wobbler wherein the wobbler position command is a function of at least one of the velocity signal representative of the velocity of the shaft and the wobbler position signal.

Abstract: A variable pressure control for controlling displacement of a variable displacement over-center pump utilizes a pair of remotely variable pressure limiter three-way valves which are associated one with each of a pair of servo cylinders operably connected to a swash plate of the pump and acting in opposition for positioning of the swash plate. The pressure limiter valves each control the communication of a servo cylinder with either system pressure or drain and are remotely operable to set a displacement of the pump and limit the pressure of the fluid delivered by the pump. This structure enables setting of pump displacement without the use of a displacement control valve associated with the servo cylinders.

Abstract: The invention relates to a pump assembly having a pump with reversible and adjustable controls, the pump controls having a neutral nonflow position and varying positions in opposite directions for effecting corresponding varying rates of flow in the opposite directions. The pump controls include a control valve for the adjusting function which is cooperable with resetting apparatus.

Abstract: A multi-function valve usable in a hydrostatic transmission and having valve components mounted in a single valve body to provide pressure limiter and high pressure relief functions and with the structure also providing a bypass function and for supply of makeup fluid to the hydrostatic transmission. The multi-function valve has a charge check valve member and a relief valve member in associated relation and movable upon the occurrence of a predetermined pressure differential thereacross to perform control functions. One pressure differential results from a flow through an orifice and with the flow being controlled by a poppet valve member normally held closed by a heavy spring which establishes a system pressure at which the pressure limiter function will occur. With this structure, the pressure limiter function occurs in advance of the high pressure relief function and under the control of a single heavy spring.

Abstract: An apparatus for use in controlling a variable displacement pump in a hydrostatic transmission comprises servo-positioning means for varying the displacement of the variable displacement pump, signal producing means for producing a first signal dependent on the rotational speed of the input shaft of the variable displacement pump and means communicating the first signal dependent on the rotational speed of the input shaft to the servo-positioning means to increase or decrease the displacement of the variable displacement pump as the rotational speed of the input shaft increases or decreases. A second signal dependent on the output pressure of the variable displacement pump is communicated to the servo-positioning means to act in opposition to the first signal to tend to reduce or increase the displacement of the variable displacement pump.

Abstract: A variable displacement pump has a swashplate controlled by a pair of pistons. A shuttle valve communicates the highest pressure pump workport to an operator-controlled displacement control valve. A pressure-responsive override valve is connected in series between the displacement control valve and the pistons. When an override pressure is achieved, the override valve blocks communication of the control valve with the pair of pistons and communicates the pump workports directly to the pistons for rapid destroking.

Abstract: A variable displacement pump has a swashplate controlled by a pair of pistons. A shuttle valve communicates the highest pressure pump workport to an operator-controlled displacement control valve. A pressure-responsive override valve is connected in series between the displacement control valve and the pistons. When an override pressure is achieved, the override valve blocks communication of the control valve with the pair of pistons and communicates the pump workports directly to the pistons for rapid destroking. A neutral bypass valve is formed out of a sleeve of the displacement control valve to bypass control pressure to sump when the displacement control valve is in neutral. A pressure-reducing valve limits the pressure acting on the stroke control valve to limit response rates and reduce erosion. The override valve includes orifices which, in intermediate positions, provide flow rate control of the fluid flow to the swashplate control pistons.

Abstract: A circuit pressure control system for a hydrostatic power transmission having a variable-displacement hydraulic pump driven by a prime mover, a hydraulic actuator for actuating a load and a displacement adjusting mechanism for the hydraulic pump. The hydraulic pump and actuator are connected together in closed or semi-closed circuit, and the displacement adjusting mechanism is actuated by a signal indicative of the operating lever manipulated variable and a signal indicative of the actual displacement of the hydraulic pump to control the speed of the hydraulic actuator.

Abstract: Disclosed is a device for controlling or measuring operational parameters of an axial piston machine. The tilting plate which engages and adjusts the stroke of the piston is provided with two opposite pivot pins supported in fixed bearings. At least one pivot pin is provided with a shearing stress sensor preferably in the form of a magnetoelastic feeler which produces electrical signals the pulsation of which is indicative of rotational speed and the magnitude of the signal is proportional to pressure applied by the pistons and thus to the delivery of the machine. A second sensor is coupled to the tilting plate to indicate the angular displacement of the latter. The output signals from the sensors are separated into the pressure dependent signals, frequency dependent signals and angular displacement signals which upon multiplication are applied to a programmable data processing unit.

Abstract: An automatic neutral point detecting system for a hydraulic pump equipped with a displacement varying device capable of shifting both in a (+) direction and in a (-) direction and connected to at least one hydraulic actuator to form a hydraulic circuit to drive the hydraulic actuator. The system includes pressure sensors for sensing the port pressures of the hydraulic pump, a shifting detector for detecting the shifting of the displacement varying device, a closing device for closing the hydraulic circuit and blocking the flow of a hydraulic fluid, a start switch for giving a command to start detection of the neutral point of the hydraulic pump, and a control unit for detecting the neutral point of the hydraulic pump.

Abstract: A failure detection system for a hydraulic pump (1) having a displacement volume varying device (1a) and connected to at least one hydraulic actuator (4) to constitute a hydraulic circuit for driving the hydraulic actuator. The system includes means (7a, 7b) for sensing the discharge pressure of the pump, means (6) for detecting the value of shifting of the displacement volume varying device, means (5, 24) for closing the hydraulic circuit to block the flow of a hydraulic fluid through the circuit, starting means (9) for giving a command to start checking on the pump to see if it is normally functioning, and a control unit (2, 23, 28, 29) for performing checking on the pump to see if it is normally functioning. The control unit includes means (S-5, S-5') responsive to the command given by the starting means for giving a command to activate the closing means, data collecting means (S-11) for causing the displacement volume varying device to shift based on information (P.sub.a, P.sub.

Abstract: The invention relates to an electro-hydraulic control system for a power drive unit having a wobbler controlled variable displacement hydraulic motor wherein the electro-hydraulic control system causes the displacement of the hydraulic motor to match a load to be driven by a power drive unit output shaft coupled to the motor. The system results in the hydraulic motor displacement matching the load as a combined function of the input command signal, the actual wobbler position, as well as the velocity and position of the power drive unit output shaft.

Abstract: A hydrostatic drive system includes a hydraulic motor driven by a variable displacement axial piston pump with alternative intake and output ports. A charge pump generates a charge pressure which is communicated only to the pump intake port via a charge valve unit. The pump displacement is controlled by a swashplate which is moved by servo pistons which receive fluid from a displacement control valve. A three check valve unit communicates the higher of pump intake, outlet and charge fluid pressures to an inlet of the displacement control valve.

Abstract: A pressure compensated pump which supplies fluid to a common header has an automatic pressure compensator adjustment mechanism which adjusts the pressure setting of the pressure compensator in response to changes in the displacement of the pump, such that the compensator pressure setting of the pump is reduced when the displacement of the pump increases to increase pump flow and the pressure setting is increased when the displacement of the pump decreases to reduce pump flow.

Abstract: An adjusting arrangement for a hydraulic pump with a variable flow quantity, having an operating cylinder located in a neutral position through the intermediary of a positively-acting resetting device, the piston of which is adjustable dependent upon the actual discharge pressure and dependent upon a parameter proportional to the actual discharge flow quantity into a position corresponding to the rated discharge flow quantity with consideration being given to the limiting value for maximum power output, maximum discharge pressure, maximum discharge flow quantity and, as required, the flow direction. An electronic control arrangement receives electrical signals corresponding to the rated discharge flow quantity and the actual discharge flow quantity and the actual pressure, which processes these signals under calculation of the actual power output and the actual pressure, and generates corresponding setting signals for the adjustment of the operating cylinder.

Abstract: A displacement control for a pump or motor having a swash plate for setting displacement includes a control device operatively connected to the swash plate and a control valve having connections to a source of pressure and drain for operating said control cylinder. The control valve has a neutral position wherein the swash plate is at or near a minimum displacement position. The control valve is operable to other positions for setting the displacement of the pump or motor and, additionally, is movable to a control position other than the neutral position or normal displacement-setting positions in response to an operative failure of the control valve positioning system which enables the swash plate to move to a position which minimizes any adverse effects from the occurrence of said operative failure. In a pump, the swash plate moves to a zero displacement position upon the occurrence of a failure while, in a motor, the swash plate moves to a maximum displacement position.

Abstract: A hydraulic circuit is provided to prevent overspeeding the prime mover powering a hydrostatic transmission. The hydrostatic transmission includes a hydraulic motor fluidly coupled to a hydraulic pump. The hydraulic pump is driven by the prime mover and the hydraulic motor drives a rotational load. The hydraulic pump includes a swash plate tilted by a servomechanism. The servomechanism receives hydraulic fluid from a pump powered by the prime mover. A valve is operated to shut-off the hydraulic fluid to the servomechanism in the event that the pressure in either of the two conduits joining together the hydraulic pump and the hydraulic motor exceeds a pre-set maximum value or if the pressure in an auxiliary line exceeds the same pre-set maximum value or if the sum of the two pressures exceeds the pre-set maximum value.

Abstract: A control for a variable displacement pressure compensated pump in which pressurized control fluid regulates the setting of a sequence valve to set the maximum output pressure of the pump and also set the displacement of the pump. The sequence valve is a two-stage device which utilizes a sequence poppet stage and cone stage. When working fluid pressure exceeds the setting of the sequence valve, the cone stage spills to reduce the displacement of the pump. If the pressure is not reduced fast enough the sequence poppet spills to more rapidly reduce the displacement of the pump.

Abstract: A radial piston device such as a radial piston motor (10) has a rotor assembly (34) rotatably positioned within a cylindrical race (43) which is movable to a first displacement position by a first piston (52) and a second displacement position by a second piston (53). A pintle (26) extends into a bore (36) of a rotor (33) of the rotor assembly (34) and has first and second ports (27,28) for delivering fluid to and from the rotor (33). In order to reduce the size of the radial piston device and to minimize the number of external lines, a control valve (66) is positioned within a bore (59) of the pintle (26) and selectively controls fluid flow from one of the first and second ports (27,28) to the first and second pistons (52,53) for shifting the cylindrical race (43) between the first and second positions.

Abstract: A variable delivery pump has a pump control mechanism in a housing secured thereto for governing directional flow of fluid through the pump, the pump being adapted to be connected through a closed loop to a motor. A pressure compensating valve is provided in the housing for governing pressure output of the pump, and a pump control cylinder is provided for positioning a flow control cam of the pump in accordance with flow of fluid through the direction control valve and the pressure compensating valve. A cam plate is coaxially connected to a directional control rotatable valve spool of the direction control valve, the cam plate having an outer periphery that is continuously radially variable from a maximum radial point to a minimum radial point for either direction of rotation of the cam from the maximum radial point as the control spool is rotated in either direction from a normal position. The cam plate actuates a cam follower, which in turn actuates a slideable sleeve in the pressure compensating valve.

Abstract: A power drive unit for operation of structure in opposite directions, such as aircraft structure and, particularly, thrust reverser structure of an aircraft engine operable between stow and deploy positions, including, a bi-directional hydraulic motor having a variably positionable wobbler for controlling displacement of the motor. Control structure includes a valve for causing fluid flow through the motor in either of two directions, a control cylinder and piston connected to the wobbler for setting the motor at either minimum or maximum displacement conditions or at any condition therebetween, a servo valve operable for setting the position of the piston in the control cylinder, and a differential area piston operatively connected to the servo valve for positioning thereof and responsive to the pressure drop across the motor in either direction of operation thereof to set the motor displacement at the least value possible for the load condition on the motor.

Abstract: Disclosed are methods and apparatus for controlling the flow of hydraulic fluid to and from a work cylinder. The disclosed system includes a reversible variable displacement pump interconnected between a work cylinder and a selector valve which may connect the pump with any of a plurality of fluid reservoirs. The fluid reservoirs contain hydraulic fluid at variable pressures so that the pressure at the work cylinder may be raised to pressures well above the pressure differential capacity of the pump at maximum flow rate by selectively increasing the pressure on the reservoir side of the pump. The system includes means for controlling the pressure at each port of the pump so that the pressue on the output port is always greater than the pressure on the input port regardless of the direction of flow through the pump and regardless of pressures at other points in the system.

Abstract: Self-contained simplified power apparatus for operating electric transmission line switches locally or remotely includes a rotary hydraulic actuator arranged for mechanical coupling to the line switch, a battery-powered reversible low voltage motor operating a reversible hydraulic pump, with the opposite ports of the pump connected respectively to the opposite ports of the hydraulic actuator for selectively producing closing and opening movements of the hydraulic actuator responsive directly to reversals in the direction of the motor and pump, means for selectively starting, stopping and reversing the motor either from a remote point or locally, and means for disengaging the operator from the line switch to permit manual operation of the latter. For line switches that require high speed closure, a modified embodiment of the invention provides electrically controlled hydraulic means to this end.

Abstract: A horsepower limiter control for an axial piston pump provides a simple adjustment for setting the maximum horsepower the pump can provide and automatically adjusts the product of working pressure and maximum pump displacement to maintain the set horsepower. The horsepower limiter control operates to reduce the displacement of the pump when working fluid pressure exceeds the setting of the sequence valve.

Abstract: A variable displacement pump having a tiltable swash plate including a pair of servo mechanisms for controlling discharge of pump fluid includes a zero displacement positioner for automatically returning the pump swash plate to a central, neutral position to discontinue pumping action if pump pressure is lost or if linkage controlling one of the servo mechanisms should break or otherwise fail.